Biosynthesis of β-Substituted Furan Skeleton in the Lower Furanoterpenoids: A Model Study

Abstract

Furanoterpenes are widely distributed in the plant kingdom. In this study we have carried out enzymatic synthesis of simple furan compounds from the molecules containing an α-isopropylidene ketone unit and the role of cytochrome P450 in this biotransformation has been conclusively established. Eight model compounds (acyclic, monocyclic, and bicyclic, 1–8), having an α-isopropylidene ketone unit, were synthesized and incubated with PB-induced rat liver microsomes in the presence of NADPH and O2. GC–MS and NMR analyses of the product(s) indicated the formation of corresponding furano derivatives (11–18). Cytochrome P450 inhibitors, metyrapone, SKF-525, and carbon monoxide, inhibited the formation of furan (8) to 76, 62, and 97%, respectively. Incubation of dehydrofukinone (7), a naturally occurring terpene, with purified cytochrome P450, NADPH–cytochrome P450 reductase, and dilaurylphosphatidylcholine in the presence of NADPH and O2 resulted in the formation of 10 and furanodehydrofukinone (19). Based on these observations, we propose one of the probable biosynthetic routes for lower furanoterpenoids in higher plants.